The optical resolution of scanners and other image capture devices is continually being increased. This increase allows a greater amount of information to be captured, which oftentimes also increases the appearance of defects or other image degradations in the high resolution captured images. As such, enhancement of the resolution while reducing the appearance of defects is becoming ever more important.
For single close-coupled device (CCD) line sensors, the sampling rate, which determines the resolution of the image, is typically determined by the center-to-center distance of the detectors in the CCD-line sensors. For multiple CCD-line sensors, the sampling rate is increased by arranging the detectors in a staggered array. More specifically, the staggered sensor array uses multiple CCD-lines that are shifted from each other by a fraction of the width of one CCD detector. The staggered arrangement of detectors improves the sample rate, but deteriorates the point spread function because it adds jaggedness artifacts.
In addition to the jaggedness artifacts, captured images also suffer from other sources of image degradation. The image degradation may be categorized as “motion blur” and “optical blur”. “Motion blur” generally occurs because the movement of the sensors produces an image that is the integration of the same object over different positions, which causes the object to appear blurred or smeared along the opposite direction of the motion. “Optical blur” generally occurs due to variations in the distance to the object from the optimal focal distance and resolution of image capture device lens.
Standard attempts at reducing or eliminating the image degradation are typically based on heuristic image enhancement methods that often fail to capture the real source of the image degradation. For example, in current implementations, because the jaggedness artifacts are more readily seen along horizontal edges, the scanned image is often smoothed in the x-direction. This approach, however, is not appropriate for high resolution applications because it blurs the image and reduces its quality. Another approach to overcoming different sources of blurs has been to sharpen the image. This approach, however, has been found, in various situations, to also sharpen the jaggedness artifacts.
An improved approach to eliminating blurs and jaggedness artifacts, would therefore be beneficial, particularly for high resolution image capture applications.